E-mail this article

To:

Invalid E-mail address

Add a personal message:(80 character limit)Your E-mail:

Invalid E-mail address

Sending your article

Your article has been sent.

The already frayed relationship between Vicki Kennedy and her late husband’s children is at the breaking point, with the two sons growing increasingly convinced that she is jeopardizing the senator’s legacy and mishandling the creation of the $71 million institute that bears his name.

Much of the conflict centers around the construction and governance of the Edward M. Kennedy Institute for the US Senate, a project that faces potential cost overruns, according to a close family friend who was authorized by some family members to speak on their behalf, but who declined to be named.

Edward M. Kennedy Jr. and Patrick Kennedy, the senator’s children, believe their father’s widow is badly bungling the efforts to create what their father had hoped would be a monument to his storied career in the US Senate, said the friend, whose account was confirmed by another close family associate.

They believe she is depending too much on a small clique of the senator’s friends and supporters, a group that lacks any figures with national stature, prominent Republicans, or even a US senator.

They are also upset that the institute’s board has yet to fulfill their request for a full financial accounting of the ongoing construction project and for strategic planning documents detailing how they plan to operate the institute.

“The children feel totally left out,’’ said the family friend authorized to speak to the Globe. “Vicki totally controls the board.’’

Lee Fentress, a longtime friend of the senator who now chairs the board, acknowledged that Edward Kennedy Jr. has conveyed his concerns to him and other members, but he insisted that the board’s dealings are transparent, the budget is under control, and fund-raising is strong. He also said the board planned to expand its membership as it moves into full operation.

“He and I have had conversations about his concerns about the size and scope of the project,’’ he said. “We have agreed to meet in the coming days to go over all this. I am convinced that once we do this, his commitments to the institution will be reinforced.’’

Fentress also offered a strong defense of Vicki Kennedy, saying she is carrying on the work that she and the senator began in 2002 to develop a vision for the institute. Vicki Kennedy declined to be finterviewed for this article.

“He treasured her counsel,’’ Fentress said. “He trusted her judgment and instincts. She was his right hand and partner in the very true sense. . . . The board of the institute unanimously agrees with his judgment of Vicki. She is a tireless and passionate advocate for the institute. We are fortunate to have her.’’

Neither son would comment publicly. But their decision to authorize a friend to share their concerns about their stepmother’s leadership role in the institute is a highly unusual public breach within the famous political family, which has traditionally strived to avoid the public airing of internal disagreements and spats.

The family friends said the sons also feel that Vicki Kennedy, who is the public face of the institute, is stepping too much into the political arena, undercutting the bipartisan spirit that marked the senator’s career and the image the institute should project.

The most notable example was the flare-up over US Senator Scott Brown’s refusal to participate in an institute-sponsored debate with Democratic rival Elizabeth Warren, because, he said, Vicki Kennedy would probably endorse her.

Besides her tussle with the two sons over the senator’s legacy, Vicki Kennedy has also become a lightning rod of discontent felt by some in the extended family, the family friends said.

Hard feelings have developed over the institute’s presence in the Kennedy family’s Hyannis Port compound. The institute, which earlier this year took possession of the original mansion and the sprawling lawn, is now charging a rental fee to the remaining family members who own property there if they want to gather on or in some way use the lawn that is the central part of the 2.4-acre waterfront lot.

The institute has also made the main house, which has been virtually unused since the senator’s death in 2009, out of bounds for use by the family.

When the singer Taylor Swift recently spent time at the compound over the July Fourth holiday, a request by the Robert F. Kennedy family to allow her to stay in the main house was rejected. The house, the original home that Joseph P. Kennedy Sr. bought in the 1920s, is slated to be used as a study and seminar center for scholars and researchers, an arrangement that the senator made in his will.

Officials at the institute say it would jeopardize its tax-exempt nonprofit status if it allowed the family to freely use the property and the house. They say the institute is legally bound to charge a rent and that the home cannot be used as a family housing unit now that the property is under the control of a nonprofit entity.

The senator envisioned the institute as a center to educate the public, students, educators, new senators, and Senate staff on the US Senate. The building will be owned by the University of Massachusetts, with construction managed by the UMass Building Authority.

The first sign of trouble came when the initial plans drawn up for the institute, by architect Rafael Vinoly, appeared to push the cost over budget. This, in turn, prompted the authority and the institute to scale back on the design.

Meanwhile, the institute has been operating without an executive director since Peter Meade, a longtime Kennedy political associate, left the position in February 2011. No full-time replacement has been found.